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FAQ

The following is a list of frequently asked questions by patients. Simply click on the questions, and the answers will appear below. If your question is not answered here, or if you require further information, please contact us.

Q.

What is an ejection fraction (EF)?

A.

Ejection fraction is a common measurement of how strong your heart is. The normal heart fills up with about 100 millilitres of blood per beat, and pumps out about 60 millilitres per heart beat. That means that the normal ejection fraction is 60 / 100 = 60%.

We consider a heart to be mildly weak if the ejection fraction (commonly called EF) is 40%-50%. We consider an ejection fraction of 30%-40% to be a moderately weakened heart muscle. Some patients have ejection fractions below 30% due to a severely weakened heart muscle.

Q.

Why is ejection fraction important?

A.

Some patients with weakened heart muscles, especially those with moderate (ejection fraction 30%-40%) or severe (ejection fraction less than 30%) impairment of heart pumping strength, are at risk for heart failure. Medications and sometimes surgical devices are administered to prevent heart failure. Such treatment is especially important for moderately or severely weakened heart muscles.

Q.

What is heart failure?

A.

Heart failure occurs when a weakened heart muscle causes a patient to experience symptoms. Common symptoms of heart failure include difficulty lying flat to sleep due to breathlessness, progressive difficulty in walking due to shortness of breath, and progressive swelling in the ankles and legs, especially first thing when you wake up. Sometimes your doctor will diagnose heart failure in a clinic, especially if symptoms are mild, for example breathlessness preventing you from climbing one flight of stairs in your home. Patients with more severe heart failure, for example severe swelling such that they have difficulty walking or breathlessness at rest, may require a visit to the Emergency Department.

The first step is to remove extra fluid by adhering to a salt free diet, and often starting a small dose of a diuretic. Next, one or two blood pressure pills (ACE inhibitors and beta blockers) are started to help strengthen the heart. The blood pressure pills are started to strengthen the heart. They may lower your blood pressure, but their benefit is in making a weakened heart stronger rather than treating your blood pressure.

Q.

Can heart failure be prevented?

A.

Yes. Many risk factors for heart failure can be identified early and treated. For example, lifestyle factors such as regular exercise and adhering to a healthy diet can prevent many conditions that can lead to heart failure. High blood pressure is one of the most important causes of heart failure, and can be prevented through regular exercise and diet. Medications to treat high blood pressure may be necessary if diet and lifestyle are not sufficient.

Q.

How is ejection fraction measured?

A.

There are 2 common tests to measure ejection fraction: echocardiography, also called echo, and MUGA, which stands for multiple gated acquisition, and is also known as radionuclide ventriculography.

Q.

What is an echocardiogram?

A.

During an echocardiogram, a technologist uses ultrasound to take pictures of the heart using a transducer which is gently placed on the chest. Pictures of the heart allow a cardiologist to estimate the ejection fraction. Echocardiograms take about 45 minutes, do not require intravenous catheters, and do not use any radiation to obtain images. Echocardiogram ejection fractions are accurate to within about 10-15 percentage points, depending on how easy it is to obtain the pictures of your heart.

Some patients have “technically difficult echocardiograms”. This is because many normal tissues can get in between the heart and the ultrasound probe, making the pictures fuzzy and difficult to interpret. It is not uncommon for women with prior left sided breast cancer treatment to have technically difficult echocardiograms. Sometimes your doctor will recommend a special type of echo called a “contrast echocardiogram”, in which an intravenous medicine is administered to help make the pictures more accurate. In other situations, a MUGA scan is suggested to measure heart function.

Q.

What is a multigated acquisition (MUGA) scan?

A.

MUGA stands for multiple gated acquisitions. It is also called a left ventricular gated scan. A MUGA scan involves an injection of a small amount of radioactive tracer which sticks to your own blood cells as blood is pumped out of your heart. By taking a picture of the blood as it is pumped out with each heart beat a MUGA scan gives the cardiologist a very accurate ejection fraction, accurate to within 5 percentage points.

Q.

Is the radiation from a multigated acquisition (MUGA) scan dangerous?

A.

The amount of radiation that you receive during a MUGA scan is small, and is equal to about 2 years worth of naturally occurring radiation, or one fifth of the annual dose that radiation workers such as the nuclear medicine technologist are allowed to be exposed to during one year.

Q.

My ejection fraction has dropped from 65 to 60 percent on echocardiograms performed while I am receiving treatment for my breast cancer. Does that mean my heart is getting weaker?

A.

No. A change of less than 10 percentage points between echocardiograms is unlikely to be a real change in the strength of your heart, and is almost always the natural change in ejection fraction that happens between tests. Small drops in ejection fraction between echocardiograms (5-15 percentage points) do not indicate heart muscle damage. Large drops in echocardiogram ejection fraction (i.e. greater than 15 percentage points), especially when your most recent ejection fraction is abnormal, may require interruption in your treatment, and sometimes referral to a cardiologist.

Q.

Does chemotherapy affect the heart?

A.

Some types of chemotherapy may lead to heart muscle weakness. Anthracycline chemotherapy is one of the most powerful drugs to eradicate cancer, but unfortunately can damage the heart muscle. Anthracycline chemotherapy agents include Epirubicin, Doxorubicin, and Mitoxantrone. Anthracyclines are important in the treatment of breast cancer, sarcoma, and many types of blood cancer.

Q.

How will I know if anthracycline chemotherapy has damaged my heart?

A.

If you receive anthracycline chemotherapy, your doctor will most likely monitor your heart function by performing a test at the start or soon after starting an anthracycline agent, and at the end of your anthracycline chemotherapy.

Q.

If anthracycline chemotherapy does damage my heart, can the damage be repaired?

A.

In eliminating cancer cells, some patients (less than 5% in early stage breast cancer) will experience a detectable drop in the strength of their heart during testing before and after anthracycline chemotherapy. If the heart muscle strength is abnormal, a cardiologist can prescribe one or two medications to strengthen the heart. This can result in a return to normal heart strength, no symptoms, and a normal life free of heart symptoms and free of cancer.

Q.

How does Trastuzumab affect the heart?

A.

Approximately 20% of all breast cancers overexpress a growth factor receptor named HER2, which may be blocked with a medication named Trastuzumab, preventing tumour growth. About one quarter of women who are treated with Trastuzumab experience a temporary, reversible weakness of heart strength. For this reason, heart tests are performed to measure heart strength during Trastuzumab treatment. If your heart test becomes abnormal, your doctor may recommend you miss one or two doses of Trastuzumab, wait for the heart to become normal again on a test, and then resume Trastuzumab therapy.

Q.

I have missed multiple doses of Trastuzumab because of my ejection fraction results on heart tests. Is there anything I can do to prevent this?

A.

A cardiologist can help advise you and your cancer doctor about how to safely receive as much Trastuzumab as you need, even if your heart tests are abnormal. Sometimes the tests are mildly abnormal, and if you have no heart symptoms, it is safe to proceed with Trastuzumab. In some patients, heart medicine is administered to boost the strength of the heart so that Trastuzumab can safely continue.